Why do children think that biological and psychological processes such as growth, illness and mood states occur? The goal of this proposed investigation is to identify if children and adults think that biological processes can be influenced by psychological factors and vice-versa. Specifically, the studies in this application examine children's beliefs about the effects of healthy/unhealthy nutrition on biological processes such as growth and psychological processes such as mood states. In contrast to most studies that have examined the effects of psychological factors on biological processes, the studies in this application examine the bidirectional effects of biological and psychological processes on one another. A series of five experiments will examine this debate by assessing children's and adults'beliefs and the underlying mechanisms children and adults are using when they reason about the impact of nutrition and mood states on biological and psychological processes. Specifically, Studies 1-3 will examine if children recognize the impact of: (a) short and long-term nutrition on the processes of growth, illness, and mood states;and (b) the impact of "yummy" healthy and unhealthy and "yucky" healthy and unhealthy foods on growth, illness and mood states. Study 4 will assess if psychological factors such as moods states can impact biological processes such as nutritional choices. Study 5 will assess the kind of input mothers give their children about the consequences of eating healthy/unhealthy foods on a long-term basis. The theoretical significance of this project will shed light on the hotly debated topic of whether children entertain a mind-body interaction when reasoning about the origins of biological and psychological processes. The data from these studies will also directly address the question as to what types of underlying mechanisms children and adults are entertaining when reasoning about the impact of biological causes on biological and psychological processes. Moreover the data will reveal if children's and adults'theories of biology are truly domain independent or interdependent. Practically, this data will inform medical practitioners if children and adults recognize that nutrition and mood states can affect biological and psychological processes such as growth, illness, and mood states. These recognitions or the lack of will strongly dictate people's dietary, lifestyle, and treatment choices which can then be used to devise effective health intervention programs. PUBLIC HEALTH RELEVANCE: People's beliefs about the role of nutrition on biological and psychological processes will dictate their dietary, lifestyle and medical treatment choices. This knowledge is essential for devising effective health intervention programs to promote healthy lifestyle choices.